LibWeb+WebContent+WebDriver: Add WebDriver endpoint to open new window

Userland/Services/WebContent/WebDriverConnection.cpp

@@ -536,6 +536,45 @@ Messages::WebDriverClient::CloseWindowResponse WebDriverConnection::close_window
     return JsonValue {};
 }
 
+// 11.5 New Window, https://w3c.github.io/webdriver/#dfn-new-window
+Messages::WebDriverClient::NewWindowResponse WebDriverConnection::new_window(JsonValue const&)
+{
+    // 1. If the implementation does not support creating new top-level browsing contexts, return error with error code unsupported operation.
+
+    // 2. If the current top-level browsing context is no longer open, return error with error code no such window.
+    TRY(ensure_open_top_level_browsing_context());
+
+    // 3. Handle any user prompts and return its value if it is an error.
+    TRY(handle_any_user_prompts());
+
+    // FIXME: 4. Let type hint be the result of getting the property "type" from the parameters argument.
+
+    // 5. Create a new top-level browsing context by running the window open steps with url set to "about:blank",
+    //    target set to the empty string, and features set to "noopener" and the user agent configured to create a new
+    //    browsing context. This must be done without invoking the focusing steps for the created browsing context. If
+    //    type hint has the value "tab", and the implementation supports multiple browsing context in the same OS
+    //    window, the new browsing context should share an OS window with the current browsing context. If type hint
+    //    is "window", and the implementation supports multiple browsing contexts in separate OS windows, the
+    //    created browsing context should be in a new OS window. In all other cases the details of how the browsing
+    //    context is presented to the user are implementation defined.
+    // FIXME: Reuse code of window.open() instead of calling choose_a_browsing_context
+    auto [browsing_context, window_type] = m_page_client.page().top_level_browsing_context().choose_a_browsing_context("_blank"sv, true);
+
+    // 6. Let handle be the associated window handle of the newly created window.
+    auto handle = browsing_context->window_handle();
+
+    // 7. Let type be "tab" if the newly created window shares an OS-level window with the current browsing context, or "window" otherwise.
+    auto type = "tab"sv;
+
+    // 8. Let result be a new JSON Object initialized with:
+    JsonObject result;
+    result.set("handle"sv, JsonValue { handle });
+    result.set("type"sv, JsonValue { type });
+
+    // 9. Return success with data result.
+    return result;
+}
+
 // 11.8.1 Get Window Rect, https://w3c.github.io/webdriver/#dfn-get-window-rect
 Messages::WebDriverClient::GetWindowRectResponse WebDriverConnection::get_window_rect()
 {